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Re: Can't get page breaks for 7 over square root of 71 meter


From: mclaren
Subject: Re: Can't get page breaks for 7 over square root of 71 meter
Date: Thu, 3 Nov 2016 19:29:49 -0700 (MST)

Hans;

You mentioned:
"LilyPond doesn't require all the barlines to align in order to be able
to break a line, it only requires an arbitrary *moment* to align. If you
have such a moment you can break lines, and the manual tells you how to
achieve that."

Sorry, no, the Lilypond manual does _not_ tell you how to achieve that. The
Lilypond manual is a mess. If the Lilypond manual were adequate, there
wouldn't be any need for a forum like this. The very existence of this forum
shows that the Lilypond manual is disorganized, incomplete, and inadequate.
I'm not the only person who has mentioned this. It's common knowledge, and
uncontroversial.

You go on to claim:

"This clearly indicates that you have a timing error *within a single
voice*, which obviously stems from the fact that 800/898 don't match
735/713. One measure is 0,890868597 whole notes long and seven eight
notes stretched by 735/413 equal 0,921610169 whole notes."

Now we're getting to the real issue. You assert that one measure of 7
sqr(71) is 
0.890868597 whole notes long. Sorry, that is incorrect.

Let's do the math:

The length of one measure is 7*square root of 71. Let's do this one
step at a time so there's no mistake. Square root of 71 = 8.42614977318.
7 of these makes 7*8.42614977318 = 58.9830484122.

Agreed?  You can check on your calculator or by typing this stuff into
WolframAlpha or google.com
to verify that this is correct.

If square root of 71 has a value of 8.42614977318, and a single eighth note
has a value of 8,
then logically 7*8.42614977318 = 58.9830484122 while a whole note contains 8
eighth notes,
so a whole note = 64
.
This means that the ratio of 7/sqr(71) to one whole note is given by

[7*8.42614977318]/(8*8).

Are you with me so far?  You can verify this with a calculator or with
WolframAlpha.

[7*8.42614977318]/(8*8) = 58.9830484122/64 = 0.92161013144.

You asserted above that "seven eight notes stretched by 735/413 equal
0.921610169 whole notes."

That is correct. Please compare 0.921610169 whole notes to 0.92161013144
whole notes, the actual value of 7*sqr(71). As you can verify, they are very
close, to within a couple of parts per million. To be exact, the difference
between  0.921610169 and 0.92161013144 is 3.756 parts in 100 million.

This is as close as I could reasonably come using rational approxmation.
Lilypond crashes and gives me an error message if I try to use a rational
fraction with really large numerators and denominators, in the tens of
millions or hundreds of millions, so as a practical matter, we must stick
with rational fractions which are in the hundreds or tens of thousands to
approximate these irrational values.

As an aside, I would say that yes, it is crazy to arbitrarily limit the
value of the Lilypond moment to rational fraction approximations. Why not
just allow floats?  What's the problem with that?  Why must a moment be a
rational fraction?  Why can't it just be a floating point number? 

In any case, let's return to the issue at hand -- which is your claim 

"One measure is 0.890868597 whole notes long."

You are incorrect, sir.  One measure of 7 sqr(71) is 0.92161013144 whole
notes long. You can check my math above. You will find that my arithmetic is
correct.

If you are saying that one measure of 7 sqr(71) is 0.890868597 whole notes
long, that's simply not right. If Lilypond is saying one measure of 7
sqr(71) is 0.890868597 whole notes long, that's also not right. 

You can follow through and veryify my math at each stage. I haven't made a
mathematical error. Lilypond is misbehaving. 

When you say "As long as you haven't got this sorted out there's not point
in discussing" you're just wrong. I have got the math sorted out and you can
verify at each step that my arithmetic is correct. 

It sounds like you don't know how to get Lilypond to force page breaks in a
score like this, and I think I can prove it.  

0.890868597 is approximated by 400/449 to an error of 53 parts in 449
billion. So I entered 400/449 into the make-moment command instead of the
values I was using.

And guess what, Hans?

Lilypond _still_ won't create a page break.  No wonder, of course --
0.890868597 whole notes is the wrong value for the length of a measure in
whole notes, way off from the actual length of a measure of 7 sqr(71), which
as we calculated above is 0.92161013144 whole notes long.  

Aside from the arithmetic errors in your answer, your reply seems like a
complicated way of saying "I don't know how to fix your problem with
Lilypond." 

In future, you may just want to say  "I don't know how to fix your problem
with Lilypond," Hans.  It's a lot simpler. 




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